NMR spectroscopic observation of a metal-free acetylide anion.

A metal-free acetylide was observed by using NMR spectroscopy. Metal-free acetylides are closely related to reactive intermediates (carbanions) in solution; therefore, they have been regarded as unobservable species. However, we generated this highly reactive and unstable species through the deprotonation of phenylacetylene by using the strong nonmetallic phosphazene base tBu-P4.